A method for regulating a fuel injection system having a quantity control valve is available. A quantity control valve of this type is usually implemented as a solenoid valve which is electromagnetically operated by a coil and has an armature and associated stroke limiting stops. The solenoid valve is open in the de-energized state of the coil. To close the solenoid valve, the coil is activated by a constant voltage—the battery voltage—whereupon the current in the coil increases in a characteristic manner. The time between the application of the voltage and the point in time when the solenoid valve closes is referred to as actuation time. After the voltage is shut off, the current drops again in a characteristic manner and the solenoid valve opens shortly after the current has dropped. The time between shutting off the voltage across the coil and the opening of the valve is referred to as extinguishing time.
In order to increase the actuation time of the solenoid valve and thus to reduce the impact velocity of the armature, the voltage applied to the coil for closing the solenoid valve may be reduced before the solenoid valve reaches an appropriate end position, i.e., before the armature hits the stroke limiting stops. The coil current and thus also the magnetic force quickly increases due to the initially applied voltage to quickly start the armature movement. An unnecessary increase in the coil current is then avoided due to the reduction of the applied voltage. The reduction may occur either before or after a certain force value at which the armature starts moving has been reached. It is important here to ensure a reliable actuation of the armature.
If the selected current in the solenoid valve is too low in operation of a fuel injection system of this type, its actuation time may occasionally be so long that the solenoid valve does not completely close in a certain actuation phase and thus sufficient high pressure may not be built up in the high-pressure pump.
In order to avoid this, the current is established so that it always ensures that the solenoid valve closes. However, the established current is often selected to be so high that it achieves a relatively quick actuation of the solenoid valve and thus produces a correspondingly high impact velocity of the armature against the stroke limiting stops, which results in a hard impact of the armature against the stroke limiting stops. In this case an audible sound is produced, which is emitted by the internal combustion engine and may be perceived as unpleasant and disturbing.